Wind

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Wind

• Wind is the general horizontal motion of air from
  one location to another based on differences in
  air pressure
• Air speed is measured by an anemometer
• Air movement is governed primarily by
• Pressure gradient force
• Coriolis force
• Friction force

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What causes wind movement

• Direction is governed by the path of least
  distance between high pressure and low pressure
• Pressure gradient
• Speed will increase if there is a larger
  difference between pressures
• Steep pressure gradient

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RESULTANT WIND

• FUNCTION OF 3 THINGS
• PGF CF FRICTION
• PGF AND CF ARE AT ODDS
• FRICTION DEFLECTS WINDS SLIGHTLY IN FAVOR OF PGF
• WHAT HAPPENS IN THE UPPER ATMOSPHERE?

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BIRDS EYE VIEW NORTHERN HEMISPHERE
H
L
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H
L
Pressure gradient
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Pressure gradient
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The Coriolis Effect

• When wind moves from zones of high pressure to
  zones of low pressure it veers due to earth
  rotation
• To the right in the northern hemisphere
• To the left in the southern hemisphere
• Equator faster rotation than the poles
• Demo
• http//www.classzone.com/books/earth_science/terc/
  content/visualizations/es1904/es1904page01.cfm?cha
  pter_novisualization

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Remembering the direction of bend in the coriolis
effect
Bends to the right
Bends to the left
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Effect of coriolis force

• Strongest at higher latitudes
• Weakest at the equator
• The effect of coriolis increases with increasing
  windspeed
• The combined effect of coriolis and pressure
  gradient force makes winds travel parallel to
  isobars
• Geostrophic Wind

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Friction force

• Effects of surface friction occur to 5000 ft
  above the ground
• Cause winds to slow down and generally move
  across isobars
• More pronounced when wind speeds are higher

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